It's funny, when I think of the game, I think of how fun the maps were, and how those built really fond memories of the whole experience. They almost feel like places I've been to, and want to go back to to have the same experience as before.
We all know that can't happen, but, I still feel a sense of nostalgia for these maps:
COD4: Every map, except Chinatown
MW2: Quarry, Rundown, Afghan (this was the first map I played with "the crew", albeit, on the wrong side. I still remember my first kills on Alpha, and my first death to Syn), Derail, Sub Base, Terminal, Highrise
BO1: I just loved this game for the HQ wreckage we threw down. Firing Range, Grid, Radiation, WMD.
After that, I have no affection for any maps. MW3 was garbage and I hated every map. Same with BO2.